IV27971: On Linux platforms, FDC records appear with probe ZF225050. Performance of user/group lookup can then be slower.

WebSphere MQ V7.5 Fix Pack 7.5.0.1
WebSphere MQ V7.0 Fix Pack 7.0.1.10

APAR status

• Closed as program error.

Error description

• On Linux platforms, when using the environment variable
  MQS_GETGROUPLIST_API=1 to cause the queue manager to use
  getgrouplist() and the user is a member of group(s) that
  contain a very large number of other users, this FDC can be
  seen.
  
  The user/group lookup operation falls back to an alternative
  method, which then succeeds, so the impact to users is minimal.
  But, because the alternative method is less optimal when using
  large groups, the result is that performance of some activities
  can be a little slower.
  
  The FDC record contains:
  
  Probe Id          :- ZF225050
  Component         :- zfuGetGroupsUsingGetgrouplist
  Major Errorcode   :- krcE_UNEXPECTED_ERROR
  
  A trace shows:
  
  --{  xcsGetgrgid
  rcunix(34) errno(34)
  --}! xcsGetgrgid rc=Unknown(FFFFFFFF)
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users on Linux platforms, when using the environment variable
  MQS_GETGROUPLIST_API=1 is in use, and the user is a member of
  group(s) that contain a very large number of other users.
  
  Platforms affected:
  Linux (Power),Linux (s390x),Linux (x86),Linux (x86-64),
  Linux (zSeries)
  
  ****************************************************************
  PROBLEM SUMMARY:
  The queue manager was querying the operating system for the
  groups in which a user belongs. The operating system was
  returning a group structure containing more users than would fit
  in the buffer being supplied. Instead of reallocating the
  buffer and retrying the operation, the WebSphere MQ code instead
  wrote the FDC and gave up, to try the less-optimal method
  instead.
  

Problem conclusion

• The WebSphere MQ code has been changed to retry the operation
  in the case where the buffer was too small. This is not an
  error case, so the FDC record is no longer written.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v7.0
  Platform           Fix Pack 7.0.1.10
  --------           --------------------
  Linux (x86)        U853084
  Linux (x86-64)     U853088
  Linux (zSeries)    U853085
  Linux (Power)      U853086
  
                     v7.1
  Platform           Fix Pack 7.1.0.3
  --------           --------------------
  Linux (x86)        7.1.0.3
  Linux (x86-64)     7.1.0.3
  Linux (zSeries)    7.1.0.3
  Linux (Power)      7.1.0.3
  
  Platform           v7.5
  --------           --------------------
  Multiplatforms     7.5.0.1
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WMQ LIN X86 V7

• Fixed component ID

  5724H7224

Applicable component levels

• R701 PSY

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